Digestion of dietary proteins is achieved by the release of proteases from the stomach and the pancreas. The release of proteases is normally tightly regulated, thereby ensuring that not too less and not too much proteolytic enzymes are secreted. This is important since a high release of proteases and a high proteolytic activity has several disadvantages. A too high release of proteases will result in energy loss and a loss of essential amino acids due to the fact that proteases themselves are highly resistant to proteolytic activity and will enter into the colon mostly unaltered. Subsequently, upon entering of an increased amount of protein (in the form of proteases) into the colon, the intestinal microbiota will ferment the proteins resulting in a disadvantageously higher pH, a shift in the composition of the intestinal microbiota and formation of toxic metabolites such as phenol, indol, and amines. This change in colonic physiology may also lead to increased intestinal infections. Finally, proteases such as trypsin are known to cleave protease activated receptors (PARs), such as PAR-II, and thereby disrupt intestinal barrier integrity. This may result in an increased abdominal pain perception. Inflammatory diseases such as IBS-D and UC have been linked to elevated levels of proteolytic activity within the intestinal lumen and subsequent PAR-II activation. Furthermore, increased faecal proteolytic activity is linked to diaper rashes. In general, a too high release of proteases will result in decreasing gastrointestinal comfort, functional digestive disorders, gastrointestinal gas formation, and/or bloating.
A too low secretion of proteolytic activity, on the other hand, is disadvantageous since in that case the dietary proteins are not properly digested leading also to loss of essential amino acids and energy, and an increased protein load of the colon.
Especially in infants and toddlers a tight regulation of protein digestion and release of proteolytic activity is of utmost importance. Firstly, for infants and toddlers a limited loss of protein is essential for good growth and development. Loss of essential amino acids and energy impairs growth and development. Secondly, the intestinal barrier function in infants and toddlers is still immature and the intestinal microbiota is still developing and therefore more susceptible for the disadvantages mentioned above. Pain perception e.g. due to colics or cramps often is a great cause of concern and initiates many doctor visits and thus reduction of the risk of pain perception, for example prevention and/or treatment of colics and/or cramps is desired.
Known ways to improve protein digestion, in particular in infants, involve partial predigestion of dietary proteins by proteases. Furthermore, Alm, 1982, J Dairy Sci 65:509-514 discloses that a low pH of milk products, especially as a result of fermentation, has a positive influence on in vitro digestibility of proteins. It is considered that in many digestive disorders the secretion of hydrochloric acid is impaired and thus the suitability of such low pH milk products is suggested for infants, children and adults. Vass et al, 1984, Acta Medica Hungarica, 41, 15-161 disclose that fermented milks have the highest protein utilization index, defined as increase in body mass in g per protein intake in g, in weaning rats, and this is attributed to a better digestibility of proteins.
Gallia Lactofidus® is an acidified infant formula, resulting from fermentation by two specific strains of lactic acid bacteria. It is disclosed that this formula facilitates the digestibility of proteins and improves the intestinal transit.
WO 2009/151330 discloses fermented infant formula with non digestible oligosaccharides for use in improving intestinal colonization in infants born via Caesarean section.
US 2011/097437 discloses nutritional compositions comprising non-digestible oligosaccharides and a protein substrate fermented with Bifidobacterium breve and Streptococcus thermophilus for use in reduction of bacterial translocation and improvement of intestinal barrier function.
US 2010/278781 discloses a protein comprising composition, fermented by Bifidobacterium breve and comprising non-digestible oligosaccharides with several health benefits.